This invention relates to flywheel type power delivery systems, such as used in motor vehicles, and more particularly, to a control system and method for efficiently operating such a power delivery system.
Conventional automotive power plant systems--wherein an engine is directly coupled to a transmission and drive line--operate on the basis of an energy creation concept. That is, only the amount of shaft energy needed to propel the vehicle at any given instant is "created" by the engine. Inherent inefficiencies in this type of system arise from the fact that the engine is called upon to deliver this energy over a fairly wide operating range, only a small portion of which typically will afford production of energy at maximum efficiency.
In an effort to improve the overall efficiency of automotive propulsion systems, flywheel type vehicles have been developed. U.S. Pat. Nos. 3,672,244 and 4,131,171 disclose two examples of such systems. In flywheel systems, shaft energy is intermittently produced by the engine over a narrower and more efficient operating range, and excess energy not required for immediate propulsion is stored as kinetic energy in a rotating flywheel of substantial mass. This stored energy typically is tapped when needed for propulsion, and the engine is recoupled to the flywheel to further "charge" it with kinetic energy when the flywheel has substantially slowed. The flywheel can also be charged by regeneration from the vehicle during braking. Significant increases in system efficiency have been realized by utilizing this "energy management" concept.
Despite developments in flywheel type automotive vehicles, there still remains room for significant improvement in overall flywheel vehicle efficiency. Kemper, Elfes and Trachman of Vadetec Corporation recognized in an October, 1980 report prepared by Lawrence Livermore Laboratory entitled "Feasibility Study Of A CVT System For An Internal-Combustion Engine/Flywheel-Drive Vehicle" that there exists a potential for a 100% improvement in system efficiency. To date this has not been realized. This invention represents a significant step toward achieving that goal.